Bad Customer service

I am very disappointed with the service of the institute, earlier last year I attempted to further my study using them. I paid the registration fee as requested. Have been waiting for my student number and the materials to study. I have never received anything from them, I even gave up. Earlier this year they are calling me to claim that I owe them a monthly fee which I don't understand is for what. They even listed me that I owe them. I can't even make a credit. because of them